Commutator



COMMUTATOR Filed Sept. 11, 1948 s f Mr/J. m m m l l l l ll|.. z l o0 3 G Wl l n-'lllll wll .2 l [im IMM \W IIMVN /ll 5 l F l ,M 0% I a0 w.

`Patented Dec. l2, 1950 UNITED STATES PATENT OFFICE Y ooMMU'rA'roR Frederick J. Durrschmidt, Shelton, Conn.

Application September 11, 1948, Serial No. 48,870

1 Claim. l

This invention relates to a commutator for electric motors and generators, and has for an object to provide a simple and improved construction in which the conductor segments are firmly and effectively anchored to keep them from shifting in operation.

It is also an object of the invention toprovide a construction and arrangement for this type of device, in which the conductor segments may be molded and anchored in molded plastic insulating material in a manner so that, when once assembled and mounted in this material, there is no chance of their shifting out of position.

With the foregoing and other objects in view, I have devised the construction illustrated in the accompanying drawing forming a part of this specification. It is, however, to be understood the invention is not limited to the specific details of construction and arrangement shown, but may embody various changes and modifications within the scope of the invention.

In this drawing:

Fig. 1 is a partial end view and partial section of a commutator involving this novel construction, the section being substantially on line I-I of Fig. 2, and

Fig.' 2 is a longitudinal section vthrough the commutator substantially on the plane of line 2--2 of Fig. 1.

In a common formof commutator a central ring or sleeve is provided with a plurality of peripheral dovetail grooves extending longitudinally of the ring in which the commutator segments with similar dovetails are inserted, the sleeve being made in two sections for mounting the segments, and the segments being separated by mica or some suitable insulation, both from each other and the sleeve. This construction is expensive, and it is very diflicult to keep the segments from shifting in operation, causing quick wear and ruining of the brushes.

With the present construction thesediculties are effectively overcome, and when once assembled the conductor segments are effectively anchored so there is no chance of their shifting. This construction comprises a central metal sleeve 5 forming the bearing for mounting on the shaft, and it is surrounded by a body 6 of molded plastic insulating material having the desired strength and electrical insulating properties. A material suitable for this use is Bakelite or similar material, but any plastic material which can be molded and can withstand a temperature of around 250 F. and necessary pressures and has the required electrical insulating properties may be used. Around the periphery of this body is mounted a plurality of metal conductor segments l, usually of copper. These segments are placed in spaced relation and each is provided with a transverse notch 8 in at least one end, but preferably in each end, and the segments are arranged so Ythat these notches of the various segments are in peripheral alignment. These are relatively wide notches as shown in Fig. 2 and divide each segment into an outer portion 9 and an inner portion I0 connected by the intermediate portion II, the inner portion I0 forming an anchoring base. Located in each series of aligned notches is a reinforcing ring I2. This may be of any material having the desired strength, but it is preferably of mild steel or similar material, and these rings are mounted in the notches over the ends of the anchoring bases I0 and are spaced from the segments.

In assembling, the segments are properly located in the mold and the plastic insulating material molded under heat and pressure about the segments and the sleeve 5, this material separating the inner edges of the segments from the sleeve 5 and also being forced into the spaces between the inner portions of the segments, particularly the anchoring base portions III, as indicated at I3, under the pressures involved, and preferably extending about one-half or one-third the distance from the inner end of the segments to their outer edges, as indicated by the line I4. This material is also molded so as to ll the notches 8 and surround the reinforcing rings I2 so as to anchor the segments in the body and also insulate the rings I2 from the segments.

It will be seen that the body, including the separating portions I3 and the portions lling the notches 8, is all one unitary integral structure. The outer portions of the segments, that is, the portions between the edges I4 of the inner insulation I3 and their outer edges or periphery are separated and insulated by separate strips of insulating material I5, preferably sheets or strips of mica, although other suitable insulating material could be used. The reinforcing rings I2 strengthen the plastic material of the bodyl to more effectively anchor the segments, and if desired to provide somewhat more insulating coverage for these rings and greater insulation in case they should be shifted outwardly somewhat during the molding operation, beads or ribs I6 may be provided over the outer edge of these rings. One outer end and edge portion of each segment may be provided with a saw cut or notch I1 for fastening the outer ends of the armature conductor wires.

Attempts have been made to use molded plastic for mounting commutator segments, but so far as applicant is aware they have not been successful. This construction with the anchoring base for the segments separated from the outer peripheral portion by the relatively wide notches in which the reinforcing rings are mounted and into which the plastic material flows under the pressure of the molding operation to ll these notches and surround the reinforcing rings, provides a very strong and rigid construction in which the conductor segments are effectively mounted and anchored so that there is no chance of their shifting out of position in operation.

Having thus set forth the nature of my invention, I claim:

A commutator comprising a body of molded insulating material, a plurality of spaced conductor segments about its periphery each provided with a notch in its opposite ends dividing the segment into an outer portion and an inner portion connected by a narrower intermediate portion, the inner portion being of less length than the outer portion and forming an anchoring base, the inner edges of the notches being concave and the outer end edges of the inner portion of the conductor segments at the entrance to these notches being convex, the segments being arranged with the notches in peripheral alignment, a reinforcing metal ring in each set of aligned notches and spaced from the segments, the material of the body extending into the notches and the rings being otherwise uncovered so that this material entirely, surrounds the rings in direct Contact therewith, said material also entirely surrounding the anchoring bases including the opposite ends thereof to anchor the segments in the body and insulate the rings from the segments, the material of the body also extending between the inner portions of adjacent segments outwardly to substanitally the inner surfaces of the rings to separate and insulate them from each other, and separate strips of insulation between the outer portions of adjacent segments and located between the outer edges of the extensions of said rst insulating means between the segments and the outer surfaces of the rings and the outer edges of the segments.

FREDERICK J. DURRSCHMIDT.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 1,255,681 Zenk Feb. 5, 1918 1,284,362 Kempton Nov. 12, 1918 1,768,654 Apple July 1, 1930 1,816,629 Werner July 29, 1931 FOREIGN PATENTS Number Country Date 468,616 Great Britain July 8, 1937 '742,586 France Jan. 4, 1933 

